Efficacy of Pseudomonas fluorescens for control of Mucor rot of apple during commercial storage and potential modes of action

2018 ◽  
Vol 64 (6) ◽  
pp. 420-431 ◽  
Author(s):  
Rhiannon L. Wallace ◽  
Danielle L. Hirkala ◽  
Louise M. Nelson
Keyword(s):  
Pseudomonas Fluorescens ◽  
Spore Germination ◽  
Biofilm Formation ◽  
Mycelial Growth ◽  
Apple Juice ◽  
Volatile Organic ◽  
Mucor Piriformis ◽  
Apple Cultivars ◽  
Space Production

The ability of Pseudomonas fluorescens isolates 1-112, 2-28, and 4-6, to control Mucor piriformis (Mucor rot) on Gala, McIntosh, Ambrosia, and Spartan apple cultivars in commercial cold storage and their possible mechanisms of action were investigated. Isolates 1-112 and 2-28 provided significant levels of disease control on McIntosh and Spartan apples, while isolate 4-6 provided control of Mucor rot on Gala and Spartan apples, compared with control fruits after 15 weeks of storage at 0 °C. Mycelial growth of M. piriformis was markedly inhibited by cell-free supernatant and volatile organic compounds produced by P. fluorescens isolates, in vitro. In filter-sterilized apple juice, living cells of all 3 P. fluorescens isolates or their metabolites significantly inhibited spore germination by 99.8% and 61.6%, on average, respectively. Electron microscopy indicated that all 3 isolates of P. fluorescens colonized the hyphae of M. piriformis, but only isolate 1-112 was observed to colonize M. piriformis spores in vitro. In the wounds of apple, all 3 isolates formed a biofilm on the fungal hyphae and on the fruit tissue. Potential mechanisms of antagonism utilized by P. fluorescens against M. piriformis may include competition for nutrients and space, production of inhibitory metabolites and volatiles, and biofilm formation, leading to inhibition of spore germination and mycelial growth.

Screening of Existing and New Boxwood Cultivars for Disease Resistance and In Vitro Fungicide Screening to Manage Boxwood Dieback Caused by Colletotrichum theobromicola

2021 ◽  
Author(s):  
Harleen Kaur ◽  
Monique DeSouza ◽  
Raghuwinder "Raj" Singh
Keyword(s):  
Active Ingredient ◽  
Spore Germination ◽  
Mycelial Growth ◽  
Management Practices ◽  
Management Strategies ◽  
Host Susceptibility ◽  
Germination Inhibition ◽  
Industry Professionals ◽  
The U.S

Boxwood is one of the most common and widely planted perennial ornamentals in both home gardens and commercial landscapes. Recently reported boxwood dieback, a fungal disease caused by Colletotrichum theobromicola, has been spreading at an alarming rate within the U.S. Boxwood breeders, nursery growers, and landscape professionals have shown great concerns regarding the lack of effective management practices. Therefore, the primary objectives of this study were to devise effective disease management strategies including screening cultivars to determine their susceptibility to boxwood dieback and screening various fungicides to determine their effectiveness in managing the disease. Host range studies were conducted by screening a wide variety of boxwood cultivars under greenhouse conditions. Although, boxwood cultivar ‘Little Missy’ showed much delayed symptom expression as compared to rest of the cultivars but none of the 11 cultivars were found to be resistance to boxwood dieback. In vitro screening of nine fungicides was conducted to determine mycelial growth as well as spore germination inhibition of eight isolates of C. theobromicola collected from eight states in the U.S. Of the nine fungicides, difenoconazole+pydiflumetofen showed maximum mycelial growth and spore germination inhibition at 1 ppm active ingredient followed by fluxapyroxad+pyraclostrobin, and pyraclostrobin+boscalid at 5 ppm active ingredient. Azoxystrobin+benzovindiflupyr significantly inhibited mycelial growth at 1 ppm but reduced spore germination at 10 ppm active ingredient. This study provides the boxwood industry professionals with critical and applied information pertaining to host susceptibility and fungicide efficacy to effectively mitigate boxwood dieback and to reduce its further spread.

scholarly journals Bioactivity of volatile organic compounds by Aureobasidium species against gray mold of tomato and table grape

2020 ◽  
Vol 36 (11) ◽  
Author(s):  
A. Di Francesco ◽  
J. Zajc ◽  
N. Gunde-Cimerman ◽  
E. Aprea ◽  
F. Gasperi ◽  
...  
Keyword(s):  
Volatile Organic Compounds ◽  
Organic Compounds ◽  
Mycelial Growth ◽  
Solid Phase ◽  
Table Grape ◽  
Conidial Suspension ◽  
Vitro Assay ◽  
Volatile Organic

Abstract Aureobasidium strains isolated from diverse unconventional environments belonging to the species A. pullulans, A. melanogenum, and A. subglaciale were evaluated for Volatile Organic Compounds (VOCs) production as a part of their modes of action against Botrytis cinerea of tomato and table grape. By in vitro assay, VOCs generated by the antagonists belonging to the species A. subglaciale showed the highest inhibition percentage of the pathogen mycelial growth (65.4%). In vivo tests were conducted with tomatoes and grapes artificially inoculated with B. cinerea conidial suspension, and exposed to VOCs emitted by the most efficient antagonists of each species (AP1, AM10, AS14) showing that VOCs of AP1 (A. pullulans) reduced the incidence by 67%, partially confirmed by the in vitro results. Conversely, on table grape, VOCs produced by all the strains did not control the fungal incidence but were only reducing the infection severity (< 44.4% by A. pullulans; < 30.5% by A. melanogenum, and A. subglaciale). Solid-phase microextraction (SPME) and subsequent gas chromatography coupled to mass spectrometry identified ethanol, 3-methyl-1-butanol, 2-methyl-1-propanol as the most produced VOCs. However, there were differences in the amounts of produced VOCs as well as in their repertoire. The EC50 values of VOCs for reduction of mycelial growth of B. cinerea uncovered 3-methyl-1-butanol as the most effective compound. The study demonstrated that the production and the efficacy of VOCs by Aureobasidium could be directly related to the specific species and pathosystem and uncovers new possibilities for searching more efficient VOCs producing strains in unconventional habitats other than plants.

In vitro evaluation of bio-agents against Pyricularia oryzae (Cav.) causing rice blast disease

2017 ◽  
Vol 37 (03) ◽  
Author(s):  
Akhilesh Kumar Kulmitra ◽  
Neha Sahu ◽  
V.B. Sanath Kumar ◽  
Thejesha A. G. ◽  
Amlan Ghosh ◽  
...  
Keyword(s):  
Bacillus Subtilis ◽  
Pseudomonas Fluorescens ◽  
Rice Blast ◽  
Mycelial Growth ◽  
Trichoderma Viride ◽  
Culture Technique ◽  
Pyricularia Oryzae ◽  
Blast Disease ◽  
Dual Culture

The five different bio-agents viz., Trichoderma viride, T. harzianum, T. virens, Pseudomonas fluorescens and Bacillus subtilis were evaluated against Pyricularia oryzae at four and eight days after incubation through dual culture technique. Among the five different bio-agents, highest per cent inhibition of mycelial growth of fungus was recorded in T. virens i.e. 67 per cent and 70 percent after four and eight days after incubation respectively with mean of 68.5 per cent followed by Trichoderma viride with the inhibition of 61 and 63 per cent respectively with mean of 62 per cent. The Pseudomonas fluorescens did not show any inhibition of mycelial growth of P. oryzae as the pathogen over grew the bio-agents.

scholarly journals Effect of Agrochemicals Used in the Cultivation of Soybean and Irrigated Rice on Beauveria bassiana (Bals.) Vuill. and Metarhizium anisopliae (Metsch.) Sorok

2019 ◽  
Vol 11 (17) ◽  
pp. 167
Author(s):  
Vanessa P. Gonçalves ◽  
Cândida R. J. de Farias ◽  
Victoria Moreira-Nunêz ◽  
Renata Moccellin ◽  
Viviana Gaviria-Hernández ◽  
...  
Keyword(s):  
Beauveria Bassiana ◽  
Entomopathogenic Fungi ◽  
Spore Germination ◽  
Metarhizium Anisopliae ◽  
Mycelial Growth ◽  
Potato Dextrose Agar ◽  
Irrigated Rice ◽  
Spray Method ◽  
Fungitoxic Effect

The objective of this work was to evaluate the fungitoxic effect of the agrochemicals used in the cultivation of soybean and irrigated rice on entomopathogenic fungi such as Beauveria bassiana and Metarhizium anisopliae by means of the mycelial growth, sporulation and spore germination. The isolates were inoculated in potato-dextrose-agar (PDA) medium containing the pesticides and exposed to spraying with the products. It was observed that chlorantraniliprole produced the best results regarding and was compatible with the two methods of contact of the product with the fungi. Flubendiamide it&rsquo;s very toxic to fungi, producing 100% inhibition when incorporated into the medium, when by spraying, the fungus M. anisopliae got mycelial growth. Etofenprox and thiamethoxam changed their toxity classification according to the method of contact with product, was moderately compatible to B. bassiana and compatible to M. anisopliae and spinosad showed more compatibility with M. anisopliae than B. bassiana and was classified as compatible. Among fungicides the tricyclazole was the only compatible with the fungus by the spray method. The results showed that in vitro agrochemicals such as tricyclazole, thiamethoxam, flubendiamide and etofenprox are harmful to fungi. It was found that environmental interference could minimize the effects on organisms, especially when the chemicals are applied by spraying.

scholarly journals Potential of antimicrobial volatile organic compounds to control Sclerotinia sclerotiorum in bean seeds

2011 ◽  
Vol 46 (2) ◽  
pp. 137-142 ◽  
Author(s):  
Maurício Batista Fialho ◽  
Maria Heloisa Duarte de Moraes ◽  
Annelise Roberta Tremocoldi ◽  
Sérgio Florentino Pascholati
Keyword(s):  
Volatile Organic Compounds ◽  
Ethyl Acetate ◽  
Organic Compounds ◽  
Sclerotinia Sclerotiorum ◽  
Mycelial Growth ◽  
In Vitro Assays ◽  
Phytopathogenic Fungus ◽  
Volatile Organic ◽  
Ethyl Octanoate

The objective of this work was to evaluate the potential of an artificial mixture of volatile organic compounds (VOCs), produced by Saccharomyces cerevisiae, to control Sclerotinia sclerotiorum in vitro and in bean seeds. The phytopathogenic fungus was exposed, in polystyrene plates, to an artificial atmosphere containing a mixture of six VOCs formed by alcohols (ethanol, 3-methyl-1-butanol, 2-methyl-1-butanol and phenylethyl alcohol) and esters (ethyl acetate and ethyl octanoate), in the proportions found in the atmosphere naturally produced by yeast. Bean seeds artificially contamined with the pathogen were fumigated with the mixture of VOCs in sealed glass flasks for four and seven days. In the in vitro assays, the compounds 2-methyl-1-butanol and 3-methyl-1-butanol were the most active against S. sclerotiorum, completely inhibiting its mycelial growth at 0.8 µL mL-1, followed by the ethyl acetate, at 1.2 µL mL-1. Bean seeds fumigated with the VOCs at 3.5 µL mL-1 showed a 75% reduction in S. sclerotiorum incidence after four days of fumigation. The VOCs produced by S. cerevisiae have potential to control the pathogen in stored seeds.

scholarly journals Variability of Three Isolates of Botrytis cinerea Affects the Inhibitory Effects of Calcium on this Fungus

2000 ◽  
Vol 90 (7) ◽  
pp. 769-774 ◽  
Author(s):  
Catherine O. Chardonnet ◽  
Carl E. Sams ◽  
Robert N. Trigiano ◽  
William S. Conway
Keyword(s):  
Botrytis Cinerea ◽  
Mycelial Growth ◽  
Dna Analysis ◽  
Epidemiological Studies ◽  
Inhibitory Effects ◽  
Apple Cultivars ◽  
Sporulation Rate ◽  
Polygalacturonase Activity

Botrytis cinerea is an economically important pathogen. Epidemiological studies are difficult because of the genetic variability within this species. The objectives of this work were to study the variability and to compare the inhibitory effects of Ca on three isolates of B. cinerea from decayed apple (B) and grape (C and C77:4). Among these isolates, B had the least radial growth but had a sporulation rate 40% higher than that of both C77:4 and C. In situ, isolate C incited the largest decay area in the fruit of two of four apple cultivars examined and had the highest polygalacturonase activity in vitro. Maximum mycelial growth was reached with CaCl2 at 1 g liter-1 for isolates B and C77:4 and at 4 g liter-1 for isolate C. Calcium (CaCl2) inhibited polygalacturonase activity at 1 g liter-1 for C and C77:4 and at 16 g liter-1 for B. Calcium infiltration reduced decay caused by all three isolates by three to five times. Mycelial DNA analysis showed that 42% of the character loci scored were polymorphic and the greatest similarities were found between B and C77:4. These results support the evidence that the biological and statistical variability in research can be affected by the B. cinerea isolate selected. Despite this variation, Ca treatment of apples reduced decay caused by all three Botrytis cinerea isolates.

scholarly journals Antifungal Activity of Quinofumelin against Fusarium graminearum and Its Inhibitory Effect on DON Biosynthesis

Toxins ◽  
2021 ◽  
Vol 13 (5) ◽  
pp. 348
Author(s):  
Qian Xiu ◽  
Lianyu Bi ◽  
Haorong Xu ◽  
Tao Li ◽  
Zehua Zhou ◽  
...  
Keyword(s):  
Antifungal Activity ◽  
Fusarium Graminearum ◽  
Spore Germination ◽  
Mycelial Growth ◽  
Marker Gene ◽  
Economic Loss ◽  
Inhibitory Effect ◽  
Head Blight ◽  
Excellent Control

Fusarium graminearum, causal agent of Fusarium head blight (FHB), causes a huge economic loss. No information is available on the activity of quinofumelin, a novel quinoline fungicide, against F. graminearum or other phytopathogens. In this study, we used mycelial growth and spore germination inhibition methods to determine the inhibitory effect of quinofumelin against F. graminearum in vitro. The results indicated that quinofumelin excellently inhibited mycelial growth and spore germination of F. graminearum, with the average EC50 values of 0.019±0.007 μg/mL and 0.087 ± 0.024 μg/mL, respectively. In addition, we found that quinofumelin could significantly decrease deoxynivalenol (DON) production and inhibit the expression of DON-related gene TRI5 in F. graminearum. Furthermore, we found that quinofumelin could disrupt the formation of Fusarium toxinsome, a structure for producing DON. Western blot analysis demonstrated that the translation level of TRI1, a marker gene for Fusarium toxinsome, was suppressed by quinofumelin. The protective and curative assays indicated that quinofumelin had an excellent control efficiency against F. graminearum on wheat coleoptiles. Taken together, quinofumelin exhibits not only an excellent antifungal activity on mycelial growth and spore germination, but also could inhibit DON biosynthesis in F. graminearum. The findings provide a novel candidate for controlling FHB caused by F. graminearum.

scholarly journals The effect of fungicides on spore germination, mycelial growth and lesion development of Phlyctema vagabunda (syn: Neofabraea alba) (bull’s eye rot of apples)

2017 ◽  
Vol 70 ◽  
pp. 112-119 ◽  
Author(s):  
P.N. Wood ◽  
B.M. Fisher
Keyword(s):  
Spore Germination ◽  
Mycelial Growth ◽  
Pathogenic Fungus ◽  
Apple Fruit ◽  
Fruit Rot ◽  
Copper Hydroxide ◽  
Lesion Development ◽  
Lime Sulphur ◽  
Bull's Eye

Phlyctema vagabunda (syn: Neofabraea alba) is a plant pathogenic fungus that causes bull’s eye rot on apples and pears. Phlyctema vagabunda fruit infections occur in orchards predominantly pre-harvest, and eventually express as a fruit rot after 4—5 months of cool storage. Twelve fungicides (captan, carbendazim, copper hydroxide, cyprodinil, difenoconazole, dithianon, dodine, isopyrazam, metiram, lime sulphur, sulphur and trifloxystrobin) were tested in vitro for their effects on spore germination and mycelial growth of P. vagabunda. Spore germination was inhibited by metiram, captan, dodine, dithianon, lime sulphur, carbendazim and isopyrazam, in order of effectiveness. Carbendazim, isopyrazam, difenoconazole and cyprodinil, in order of effectiveness, inhibited mycelial growth when used at label rates. Wettable sulphur was ineffective in both assays. On detached apple fruit, carbendazim, cyprodinil, trifloxystrobin and isopyrazam (in order of effectiveness) inhibited lesion development.

scholarly journals Biological Management of Colocasia Blight Incited by Phytophthora colocasiae using Native Strains of Antagonists in North Western Himalayas

2021 ◽  
Author(s):  
Divya Bhandhari ◽  
Amar Singh ◽  
J.V. Patel ◽  
D.K. Banyal
Keyword(s):  
Growth Inhibition ◽  
Disease Control ◽  
Pseudomonas Fluorescens ◽  
Mycelial Growth ◽  
Antagonistic Activity ◽  
Trichoderma Spp ◽  
Phytophthora Colocasiae ◽  
Biological Management

Background: Colocasia is cultivated globally for its edible corm and leaves. Leaf blight incited by Phytophthora colocasiae is the most destructive disease of colocasia. The current study aims at biological management of the disease. Methods: Nine Trichoderma isolates from the colocasia rhizosphere soil along with five designated isolates of Trichoderma spp. already available in the Department of Plant Pathology, CSK HPKV, Palampur were tested in vitro for antagonistic activity against P. colocasiae. Similarly, six unidentified bacterial strains isolated from colocasia phylloplane and available Pseudomonas fluorescens were evaluated for antagonistic activity against P. colocasiae under in vitro conditions. The bioagents found best under in vitro conditions were evaluated in vivo. Result: Trichoderma isolate Ti-6 was found significantly superior bioagent as it resulted in 72.9 per cent mycelial growth inhibition of P. colocasiae followed by Ti-5 (63.2%), Ti-4 (60.1%) and Ti-1 (54.5%). Amongst bacterial antagonists, Pseudomonas fluorescens gave maximum mycelial growth inhibition of 50.5 per cent followed by Pb-3 (31.4%) and Pb-6 (30.5%). The efficacy of five Trichoderma spp isolates viz., Ti-6, Ti-5, Ti-4, Ti-1, T. viride and one bacterial isolate of P. fluorescens found effective under in vitro were also evaluated in vivo using three delivery systems under net house condition. Corm treatment with bioagents was found superior for management of colocasia blight. Corm treatment with Ti-6 was found to be significantly superior to other treatments as 93.74 per cent of disease control was observed. For drenching, bioagent Ti-6 was proved best in managing blight disease (88.91%) followed by Ti-5 (88.90%). However, Ti-5 isolate of Trichoderma sp. as soil application was found superior with 90.02 per cent disease control.

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